I didn't become a general of the First Order at a very young age for no reason.

[He doesn't mind discussing some of this with Ren. It's not like he has to worry about him taking his place as a general, even though they are both seeking power in the First Order. Ren just has no interest in the military, something that is beneficial to him in this regard. Plus, he can recognize that their strengths are vastly different from each other.]

A lot of it was waiting for the right opportunity to put someone down.